(Ari Melber is a co-host of "The Cycle" on MSNBC. The opinions expressed are his own.)

By Ari Melber

March 13 (Reuters) - The new Congress versus the CIA battle over "hacking" Senate computers and "spying" isn't about surveillance. It's about torture.

We have never had a full reckoning for our government's use of torture on terror suspects after September 11. There were no prosecutions of military officers or senior officials. (One soldier was imprisoned for abuse at the Abu Ghraib prison, former Corporal Charles Graner, while four officers received administrative demerits, not prosecution.) Remarkably, there has not even been a full release of classified government investigations into U.S. torture. It's hard to get accountability in the dark.

That repressed history is the real context for the remarkable fight that spilled into public view when Senator Dianne Feinstein (D-Calif.) spoke on the Senate floor on Tuesday.

There have been attempts by Congress, human rights groups and the press to pursue information about the torture - or "enhanced interrogation" program - that the Bush administration's CIA began in 2002.

The exposure of torture at Abu Ghraib prison in Iraq appeared in a 2004 Seymour Hersh article in the New Yorker, not from the government. Further public reports pushed President George W. Bush to disclose and defend the program in 2006.

Leaks then surfaced about crucial evidence that documented some interrogation sessions, which could factually resolve debates between the administration and critics over how far the interrogation went. The CIA had recorded the interrogation sessions. Before Congress or independent investigations could review the video tapes, however, the CIA's lawyers destroyed them in 2007. In many contexts, that action alone is a crime - obstruction of justice.

Congress responded to the destruction of the tapes by launching a limited review of those interrogations. In 2009, the review found the CIA sessions were different, and far harsher, than the agency had claimed.

This drove the usually hawkish Senate Intelligence Committee, headed by Feinstein, to a bureaucratic breaking point. Faced with the CIA's apparent misrepresentations and possible criminal obstruction to cover up a possible crime, the panel held a bipartisan vote to conduct a full investigation.

The revelations about the CIA's continued efforts to subvert that investigation is what sparked the current constitutional crisis - and the unusual floor speech by Feinstein, a longtime CIA ally.

Feinstein recounted how her committee "voted 14 to 1 to initiate a comprehensive review of the CIA detention and interrogation program," because it learned "the interrogations and conditions of confinement at the CIA detention sites were far different and far more harsh than the way the CIA had described them to" Congress.

She recounted how Senate investigators strained to accommodate CIA requests for this "independent" review, such as going to a CIA site to review digital files that remained under the agency's control. When the CIA learned that the Senate staff found incriminating internal CIA notes about the files, which reportedly contradicted the CIA's public claims about the program, Feinstein said the CIA began looking into the Senate investigators' work.

In other words, the CIA began investigating the investigators.

Feinstein says that act may be illegal, violating "the Fourth Amendment, the Computer Fraud and Abuse Act, as well as Executive Order 12333, which prohibits the CIA from conducting domestic searches or surveillance."

CIA Director John Brennan responded with a parsing denial, saying there has not been a "tremendous" level of CIA spying or hacking of Congress. What about, say, a small amount of illegal spying?

Other statements from Brennan and administration officials lean heavily on capacious words like "hacking" and "spying," which have notoriously vague meanings, and plenty of wiggle room.

It doesn't stop there. The most dangerous part of this crisis does not turn on the definition of hacking. It doesn't depend on whether the CIA maliciously tried to kneecap the investigation, or just found ways to accidentally kneecap it.

The most dangerous move came from what the CIA did with the information that it gleaned from monitoring the Senate.

A top CIA lawyer took one of the most severe legal actions possible - officially asking the Justice Department to consider prosecuting the Senate investigators for doing their jobs.

Feinstein, backed by colleagues in both parties, said this tactic is an illegitimate attempt to get Senate staff to back off.

"There is no legitimate reason to allege to the Justice Department that Senate staff may have committed a crime," she said on the Senate floor. "I view the acting general counsel's referral as a potential effort to intimidate this staff - and I am not taking it lightly."

This week, I spoke with congressional staff members who said even a small risk of prosecution for investigating the CIA would have a chilling effect.

Feinstein also drew a direct line from the CIA's aggressive, provocative move, which threw the grenade of a separation of powers crisis into President Barack Obama's Justice Department - back to exposing the history of torture. Where this all started.

"The staff members who have been working on this study and this report have devoted years of their lives to it," she explained, "They are now being threatened with legal jeopardy, just as the final revisions to the report are being made so that parts of it can be declassified and released to the American people."

These are remarkable public charges from one of the intelligence community's most experienced allies in Congress -- that when it comes to covering up torture, the CIA will try to criminalize public service and oversight itself.

This is not an academic exercise. The CIA's moves already have practical consequences.

Right now the Justice Department, which closed its own criminal investigation into torture by U.S. officials with no charges, is reviewing a high-level referral to investigate and possibly charge U.S. officials for investigating torture.

This is more than backward - it is dangerous for our separation of powers. Do we have a functioning democracy? Or are we sliding into a system where there are checks and balances for the rest of us, but no rules for the CIA?

Obama largely ducked the big questions on Wednesday, saying the investigations will play out, but he is "absolutely committed to declassifying" the torture report. But it is Obama's employee, Brennan, who has been fighting that declassification.

So who is in charge here? The president either needs to get his CIA director in check, or get a new CIA director. (Ari Melber)